Method for producing slip-resistant textile materials



METHOD FOR PRODUCING SLIP-RESISTANT TEXTILE MATERIALS Donald H. Powers, Concord, and William 'Jrllai rison, Reading, Mass, assignors to Monsanto Chemical Company, St. Louis, Mo., a corporation of Delaware No Drawing. Application April 14, 1945, Serial No. 588,422

This invention relates to the treatment of textile yarns or fabrics for the purpose of improving their properties, and particularly relates to the treatment of yarns or fabrics with colloidal dispersions of silica to reduce slippage, in-

crease their tensile strength and improvetheir finish.

According to the prior art, it is old to apply silicic acid gels or silica gels on fabrics for the purpose of waterproofing or flameproofing them, or to increase the absorbent powers of such materiais as filter cloths, bandage material or gas absorbent clothing.- Such treatment has also involved the deposition of unusually large amounts of silica gel, and has failed to accomplish the muitifold purposes contemplated herein.

It is a primary object of this invention to treat yarns and fabricsin such amanne'r as to impart a full, dry, non-slip finish, thereto, increase their tensile strength, and in general impart improved properties to the yarn or fabric such as those hereinafter further described.

A further object is to prepare yarns and fabrics from textile fibers treated with the hereindescribed colloidal dispersions or solutions of silica.

Still further objectsand advantages of the invention will appear from. the following description and appended claims. Before explaining in detail the present invention, however, it is to be understood that the invention is not limited in its application to the details described herein, since the invention is capable of other embodiments-and of being practiced or carried out in various ways.

The invention is based on the discovery that remarkable and unusual properties may be imparted to yarns and fabrics by treating. them with certain extremely fine colloidal solutions or dispersions of polymerized silica. In carrying out the invention, the colloidal solutions employed should preferably be-reiatively dilute, but they may be used in widely diil'erent concentrations, depending on the type of apparatus used to apply them to the yarn or fabric. The purposes of the invention are in general accomplished by applying to the yarn or fabric, a sufilcient amount of the colloidal solution or sol to supply from 0.1 to 5.0% silica based on the weight of the. yarn or fabric being treated. However, in some in stancesit is desirable to apply larger amounts of silica to the yamor fabric, as when a harsh and/or stiif finish is desired, and in such cases it is practical to employ amounts as high as After being applied, the sol or solution on the 10 Claims. (Cl. 117-1395) yarn or fabric is dried, which may or may not require special drying equipment, depending on whether subsequent treatment of the yarn or fabric involves subjecting the material to drying conditions. Preferably, the yarn or fabric is passed over steam heated dry caps or infra red heated tenter frames maintained at a temperateure of about 200 F. or higher, but not high enough to damage the fabric. By treating the fabric in this manner, an inorganic resinous film is applied, as indicated by the fact that the resulting material is substantially dust free, relatively wash fast, and appreciably firmer and fuller than prior to treatment. In this respect the treated fabrics of this invention differ decidedly from the gel treated fabrics of the prior art. In some cases it is possible to dry the yarns or fabrics at lower temperatures. and even as low as room temperature.

Prior to application to the yarns or fabrics it is usually preferable to add a small amount of a suitable wetting agent to the colloidal solution or sol, as this tends to increase the penetration of the solution and enhance its sli proofing action and other properties. Good results, however, can frequently be'obtained in the absence of such an agent. Moreover, whether or not a wetting agent is employed, it is sometimes desirable to add a softening agent to the solution.

The colloidal solutions used in accordance with the invention are preferably made by reacting an acid, such as a mineral acid or any other acid capable of forming salts byreaction with silicates with a water-soluble silicate in the manner customarily employed to form silica gel, washing the resulting gel with water to remove the electrolytes formed during the reactiomcovering the gel with a weak aqueous solution of a substance ca pable of forming hydroxyl ions and, after removing the gel from the solution, heating the gel, while avoiding evaporating of water, until subsequently all of the gel is converted to a sol. A more complete description of the manufacture of the above type of sol may be obtained in the co-,

pending application of John F. White, Serial Number 485,493, filed May 3, 1943, and granted May 8, 1945, as Patent No. 2,375,738.

Solutions prepared in the above manner are preferred, since they are stable for an indefinite period of time. Moreover, the silica contained therein has a larger particle size than the silica in other types. of sols, and since they are usually prepared in a neutral or slightly alkaline state, they are admirably adapted for the purposes of this invention. It is possible, however, to prepare the colloidal solutions as described above, then to acidify them and use them in a slightly acid condition, when desired. Other types of colloidal solutions or sols of silica may also be used, particularly when slip proof qualities are not required to ,a high degree. For example, the sols prepared by reacting water-soluble silicates with an acid and subjecting the acidified silicate to treatment with alcohol and/or to cooling to remove the electrolyte, as described in the U. S. patent to Morris D. Marshall, number 2,285,449 and the U. S. patent to John F. White, number 2,285,477, may be used if desired. It is also possible to use sols prepared by treatment of an alkali silicate with ion-exchange material, as described in the U. S. patent to Paul G. Bird, number 2,244,325, as well as anhydrous organosols. However, the anhydrous sols are not as suitable as those containing a preponderant amount of water or consisting of silica and water.

The concentration of the colloidal solution or sol used is relatively unimportant, as it is possible to employ a wide variety of solution strengths depending upon the type of apparatus used or the degree of pick-up which is possible in the particular apparatus employed for applying the sol. Generally, however, it is preferable to employ solutions having an SiO2 concentration between 0.1 and about although concentrations as high as 30% can be used.

A wide variety of wetting agents may be used in accordance with the invention, including such substances as the sodium salts of alkylated benzene sulfonates, such as sodium octyl benzene sulfonate and sodium decyl benzene sulfonate; sodium lauryl sulfate, the sodium salt of methyl stearamide ethionic acid, dioctyl sodium sulfosuccinate and the like. Suitable softening agents include neutral type softeners, such as aqueous emulsions of oils, fats, waxes and fatty acids, including stearic, oleic and palmitic acids or mixtures thereof; and cationic type softeners, such as cetyl dimethyl benzyl ammonium chloride and the quaternary ammonium salts of diethyl aminoethyl oleyl amide hydro-acetate. The wetting agent, if used should be present in amounts varying from 0.1 to 5% of the colloidal solution, while the softening agent should be added in amounts varying from 0.03 to 3% of the solution.

To increase the wash fastness of the silica deposited in the fibers of the yarns and fabrics, various resins or resin formers may be added to the silica s01 prior to its application to the yarn or fabric. Examples of the resins which may be used are aqueous emulsions of polyvinyl chloride, polyvinyl acetate, polymers of methyl methacrylate, polyvinyl formal, polyvinyl butyral, rubber latex, polystyrene, copolymers of these resins and the like. Various emulsifying agents such as sodium oleate, casein and the like may be used to prepare these emulsions, and in general these emulsions contain from to 40% resin. Aqueous solutions of various resins may also be used, such as polyvinyl alcohol, mono or di alkylol ureas, such as methylol urea; di to hexa alkylol melamines, such as di, tri or tetra methylol melamine; alkylated alkylol ureas and alkylated a1- kylol melamines, such as methylated, ethylated or butylated methylol urea or methylated methylol melamine. Ethylated or butylated methylol melamine may also be used, if desired, but must be in the form of an aqueous emulsion. These alkylated compounds are preferably prepared by reacting the alkylol urea or melamine with an alcohol, such as methyl, ethyl or butyl alcohol.

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Varying amounts of these resins may be added to the silica sol or solution, and when the resin is used principally to increase the wash fastness of the silica deposited in or on the fibers, the amount of resin deposited in or on the fibers should be within the range of 0.1 to 5%, but in general, the weight of the resin should be substantially equal to or less than the weight of the silica deposited in or on the fiber. However, if it is desired to impart additional properties to the fabric, such as crease resistance and resistance to shrinking, the amount of resin used with the silica sol or solution may' be adjusted so that as much as 10 to 20% of resin will be deposited on the fabric. When resins are used with the silica sols, it is usually desirable to dry or set the resin by heating the treated fabric or yarn at temperatures above 200 F., but not high enough to damage the fabric. However, it is sometimes possible to dry at room temperatures, as when the resin does not require curing, as in the case of polyvinyl alcohol.

Instead of resin solutions, aqueous solutions of methyl cellulose may be used for the same purpose.

A further understanding of the invention will be obtained from the following examples:

Example I mixture set to a gel a few minutes after the mixing was completed. After 16 hours aging the syneresis liquor was siphoned off and the gel crushed to one inch lumps. These lumps were washed with a continuous flow of water for 16 hours. The washed gel was then covered with seven hundred and fifty pounds of water containing 0.9 pound of NaOH. After standing 6 hours the excess solution was drained off and a portion of the gel was charged to an autoclave. The gel was heated for three hours, using steam at two hundred and fifteen pounds per square inch absolute pressure in the jacket of the autoclave. The contents of the autoclave were then blown out and the small amount of residual undispersed gel was removed by filtration. The solution so produced contained about 12.5% SiO2 and was giilslted with water until it contained only 0.1%

In making sols as illustrated by the foregoing examples, the aging step may be omitted entirely but it is preferable to age for at least a few hours. The time the gel remains standing in the caustic soda solution may be as little as 30 minutes. Moreover, the time the gel remains in the autoclave may also be varied, depending upon the size and shape of the autoclave used.

Bleached cotton sheeting was immersed in the silica sol prepared as described above, and after passing through the sol was run through a padder adjusted for pick-up. The fabric was then framed and dried in a conventional drying oven at a temperature of 250 F. In comparison with untreated sheeting of the same type, the treated fabric had more fullness of hand and greater slip resistance and tensile strength.

to treatment.

Example If with 293 pounds of water and charged to a mix-- ing tank. Four hundred and seventy-two pounds of a sodium silicate solution analyzing 8.9% M120 and 29% S102 were diluted with three hundred and seventy-seven pounds of water and added with stirring to the acid solution. The mixture set to a gel a few minutes after the mixing was completed, and the resulting gel was further treated as described in Example I with the formation of a colloidal'solution or sol containing about 12.5% $102. This was then diluted with water until it contained about silica, after which suflicient dioctyl sodium sulfosuccinate was added to provide about 0.25% in the solution.

Bleached cotton sheeting was immersed in the diluted sol, and-then run through squeeze rolls adjusted for 95% pick-up. After being treated in this manner the fabric was framed and dried. The resulting fabric was considerably stiffer than before treatment, yet did not dust out. Although washing reduced the stiffness somewhat, the treated and washed fabric was nevertheless fuller than untreated fabric, and displayed a considerably greater tensile strength and resistance to slippage.

Example III A colloidal solution of silica containing about 12.5% silica. was prepared as described in Example I, and then diluted with water until it contained only about 1.0 silica. To this was added sufficient sodium decyl benzene sulfonate to provide about 0.5% in the solution. Dyed wool fabric was immersed in the resulting bath and then passed through squeeze rolls adjusted for 100% pick-up. Upon being framed and dried, the fabric showed greater tensile strength and a higher coefficient of friction than the same fabric prior Example IV Example V Spun rayon fabric was treated with an aquasol prepared as described in Example I, and diluted to a silica content of 2.0% by immersing the fabric in the diluted sol and passing it through a padding machine adjusted for 100% pick-up. After being dried the fabric possessed a dry finish similar tothat of real silk, a fuller hand than similar untreated fabric, and aiso had a delustered appearance without addedopaqueness.

Example VI An aquasol was prepared as described in Example I, and then diluted with water until it contained about 8% silica. The resulting sol was applied to spun rayon fabric by immersing the fabric in a bath containing the sol and passing the treated sol throughsqueeze rolls adjusted to Dyed wool fabric incorporate in the fabric an amount by weight of through squeeze rolls adjusted for 100% pick-up. After being dried, the resulting fabric did not the sol equal to the weight of the fabric. After drying, the fabric possessed a dustless stiff finish. and had a delustered appearance without any added opaqueness. Laundering reduced the stiffness, but a marked fullness of hand was retained as compared with untreated fabric.

Example VII Knitted filament rayon fabric, treated with an aquasol prepared as described in Example I in such a manner as to deposit on the rayon 0.6% silica based on the weight of the rayon, was rendered snag resistant and possessed greater abrasion resistance than the same material prior to treatment. It also had a delustered appearance without any added opaqueness.

Example VIII An alco-aquasol was prepared as follows:

Three hundred and fifty-eight pounds of sodium silicate comprising 28.7% $102, 8.9% NazO and 62.4% H2O were diluted with 162 pounds of water. The resulting mixture was added to 163.5 pounds of 31% sulfuric acid, after which the mass was agitated to distribute the silicate throughout the acid. Nine hundred pounds of commercial ethyl alcohol were then added to the mixture, which was in the form of a silica sol. Upon addition of the alcohol, sodium sulfate precipitated out and was removed by filtration. The resulting sol was diluted with water to a concentration of 1.5% silica.

Cotton sheeting was immersed in the diluted sol prepared as described above, and then passed dust, possessed a full firm hand, as well as approximately twice the resistanceto slippage displayed by the fabric prior to treatment.

Example IX An alco-aquasol was prepared as described in Example VIII, but diluted to a 6% silica concentration. Cotton sheeting was then treated with the resulting sol by immersion in a bath containing the sol, after which the fabric was passed through squeeze rolls adjusted for 100% pick-up. After being treated, the fabric possessed a stiff papery finish which was substantially dust-free. It also had greater resistance to slippage than the same material had prior to treatment.

Example X An alco-aquasol was prepared as described in Example VIII, but diluted to a concentration of 1% silica. The resulting so] was applied to spun rayon fabric by immersion of the fabric in the sol, after which the fabric was passed through 9. padding machine adjusted for 100% pick-up. After being dried, the fabric possessed a firm delustered finish and greater tensile strength than it had prior to treatment.

Example XI Spun rayon fabric was immersed in an alcoaquasol prepared as described in Example VIII, but diluted to a concentration of 6% silica, after which it was passed through squeeze rolls adjusted for 100% pick-up. After being dried, the fabric displayed a stiff papery finish and had a delustered appearance without any opaqueness.

Example XII An aquasol containing 0.5 silica was prepared polymer of adipic acid and hexamethylene di- 7 as described in Example I, and then applied to Nylon sutures in such a manner as to deposit on the Nylon 0.5% silica based on the weight of the Nylon. Upon being dried, the sutures possessed a resistance to slippage, which was considerably greater than that of the untreated sutures.

Example XIII A silica sol containing about 12.5% silica was prepared as described in Example I, and then diluted with water until it contained about 0.5% silica. To this was added sufficient sodium decyl' benzene sulfonate to provide about 0.2% in the solution. Bleached cotton sheeting was immersed in the diluted sol, and then run through squeeze rolls adjusted for 95% pick-up. After being treated in this manner, the fabric was framed and dried. In comparison with untreated sheeting of the same type, the treated fabric had more fullness of hand and greater slip resistance and tensile strength. Also it was superior in these qualities to similar fabric which had been treated with the same sol, but in the absence of the sulfonate. 25

Example XIV Fine cotton sheeting was immersed in a bath of a silica sol of the type used in Example II, and a similar treatment was applied to the sheetingin a similar silica sol bath to which a small amount of polyvinyl alcohol resin had been added. After air drying at room temperature, the sheeting was then given several 15 minute washes in a 0.25% aqueous soap solution at 100 F. The following table of data shows the amount of silica that was retained on the fabric after the several successive washings. The amount of silica on the fabric treated in Bath 1 was 0.3% by weight. The amounts of silica and resin on the fabric treated in Bath 2 were 0.3% and 0.1% respectively. For the purpose of these tests the amount of silica present in the fabric prior to washing is taken as 100%.

Percent of original silica retained on sheeting afte1 laundering Number of Wastes The sheetings treated as described above were all superior in tensile strength to the same sheeting which had not been treated with the silica sol. These data illustrate the wash fastness which may be obtained by usingsilica sols containing resins of the types hereinbefore described.

In the examples reference is made to the treatment of cotton, wool and rayon fabrics and Nylon sutures. It should be understood, however, that as equally good results can be obtained with all types of textile materials, including in addition to those named above, cellulosic materials, such as cellulose nitrate, cellulose acetate, viscose, cuprammonium rayon and high tensile strength rayon; portein materials, such as natural silk and fibers made from the casein in milk; synthetic materials, such as fibers made of the copolymer of vinyl chloride and vinylidine chloride, the coamine, the copolymer of vinyl chloride and vinyl acetate, and glass fibers; and yarns and fabrics containing mixtures or blends of any two or more of the above materials.

The sols described herein may be applied either by spraying or by immersion, either with or without the assistance of padding or squeeze rolls or other types of extracting equipment. As a wide choice may be made in the strength of the solution used, it is possible to use all types of apparatus in applying the sols. Thus the desired amount of silica may be readily applied to the yarns or fabrics by adjusting the concentration of the solution in accordance with the amount of .pick-up possible with the particular apparatus vention usually have, as initially prepared, a

pH ranging from about 7 to 10. It is possible, however, to employ the sols at a somewhat lower pH, if desired, as for example where an acid reacting sol is desired. Thus, the sols may be applied to the fibers within the range of 4 to 10 pH, depending on requirements and the most suitable pH for the particular fibers bein treated.

By examination in the electron microscope, it has been observed that the colloidal particles in these preferred sols have a generally spherical shape. Moreover, they vary in size from about 40 to 80 millimicrons in diameter with the average particle in most instances about millimicrons in diameter.

Yarns and fabrics treated with the sols of this invention possess a fullness whichisretained after washing, and have a delustered appearance without added opaqueness. The sols also impart to yarns and fabrics a greater coeflicient of friction or slip resistance than similar untreated yarns possess. This in turn results in yarns or fabrics of greater tensile strength. By virtue of this increased tensile strength-one can prepare a silica sol treated yarn or fabric from a yarn which, before treatment, has a lower number of turns per inch than its optimum number of turns per inch for'maximum strength and, after treatment, has a higher tensile strength than the untreated yarn. Fine knit goods, such as hosiery, show a markedly increased wear, run and snag resistance, when treated with the sols made in accordance with the processes described herein.

Moreover, the treated fabrics also tend to have a dry finish, which in the case of spun rayon gives the fabric a dry handle usually associated with natural silk. When relatively large amounts of the sols are applied to the fabrics, i. e. sufficient to deposit between 5 and 10% silica on the weight of the fabric, an unusually harsh and/or stiff finish is obtained, which is frequently desirable on cotton and rayon fabrics.

When the sols are applied to Nylon sutures, the sutures tend to remain knotted under actual conditions of use. Moreover, tire cord, when treated as described herein, is less apt to separate from the surrounding rubber in view of the greater slip resistance of the cord, and for this reason the cord has a much longer life. Other similar materials, such as fishing lines, cords, threads. ropes and cables are also greatly improved by the treatment described herein in viewv of the greater tensile strength thereby obtained.

mersing the sliver or roving in the sol, after which the fibers are dried either during subsequent operations or with the aid of special drying equipment. It is usually sufficient to apply or deposit on the fibers an amount of silica varying from 0.1 to 3% based on the weight of the fibers. However, in some instances it is desirable to use larger amounts, as when a harsh and/or stiff finish is desired, and in such cases it is possible to employ amounts up to 4 or By following any of these methods it is possible to pro-' duce, from the treated or slip resistant fibers, yarns having the same or greater tensile strength than the untreated yarn even though the number of turns per inch of the treated yarn is substantially less than the number of turns per inch required to give maximum strength to the untreated yam. This is illustrated by the following tests on cotton yarn prepared from 11 inch staple cotton by passing card sliver below rolls through a vat containing the silica sol and a wetting agent. The treated sliver was then passed through a pair of squeeze rolls, dried and spun into yarns of diflerent turns or twists per inch. The following data show tensile strength values of yarns of different twists per inch and different yarn number prepared from both treated and untreated fibers.

Strength in pounds oi Standard 120 Yard Skeins of 11's Yarns Number m? Fiber Fiber Fiber W Untreat- Treated Treated Treated Dd With 1% With 2% With 3 Silica Sol Silica Sol Silica S01 Strength in unds of Standard 120 Yard S eins of 22's Yarns i i i o w s Fiber Fiber Fiber per inch Untreat- Treated Treated Treated ed With 1% With 2% With 3% Silica S01 Silica Sol Silica S01 In each of the slivers treated the squeeze rolls were adjusted to pick up a weight of solution equal to the weight of the sliver, which deposited in the fiber 1, 2 and 3% of silica respectively, based on the dry weight of the fiber.

This increase in tensile strength of yarns or fabrics, prepared from fibers treated as described The unusual advantages obtained as a result of the application of the sols described herein are believed to be due to the sub-microscopic roughness imparted by the deposit of exceeding ly small particles of silica in the form of an inorganic resinous film. The silica is in any case polymerized, or partially polymerized and produces films which have markedly difierent properties and effects on the yarn or fabric as compared with depositions of silica gel.

This application is a continuation-in-part of our copending application, Serial Number 546,753, filed July 26, 1944 and now abandoned.

This application is also copending with our application Serial .No. 588,420, filed April 14, 1945, which claims a stocking having silica deposited thereon.

What we claim is:

1. The method of treating textile fabrics to provide them with a slip-resistant finish which comprises applying to the outer surfaces of said fabric an aqueous colloidal solution of silica consisting of a stable silica sol in an amount sufficient to supply from 0.1 to 5% of silica based on the weight of the fabric and sufllcient to form a film of silica on the surface of said fabric upon drying, and then drying the treated fabric by exposure to temperatures of at least 200 F. without allowing said solution to convert to a gel, whereby an inorganic resinous film composed of particles of silica is formed thereon.

2. The method of treating textile fabrics to provide them with a slip-resistant finish which comprises applying to the surface of said fabric an aqueous colloidal solution of silica consisting of a stable silica sol in an amount sufiicient to supply from 0.1 to 5% of silica based on the weight of the fabric, and drying the fabric thus treated by exposure to temperatures of at least 200 F. without allowing said solution to convert to a gel, whereby an inorganic resinous film composed of particles of silica is formed thereon.

centration of silica between 0.1 and 30%, and

thereafter drying the fabric by exposure to temperatures of at least 200 F. without allowing said solution to convert to a gel, whereby an inorganic resinous film composed of particles of silica is formed thereon.

4. The method substantially as described in "claim 1. but further characterized in that the colloidal solution employed is an aquasol.

5. The method substantially as described in claim 1, but further characterized in that the colloidal solution employed is an organo-aquasol. 6. The method substantially as described in claim 1, but further described in that the colloidal solution is applied to the fibers by spraying.

'7. The method substantially'as described in claim 1, but further characterized in that the ll colloidal solution is applied to the iabric by immersion oi the tabrlc thereim aiter which the excess solution is squeezed out at; the fabric.

8. The method suhstantially as described in claim 2. but iurther'characterised in'that the colloidal solution has added thereto a small amount of a wetting mm;

9. The method substan llyas described in claim 2, but further 'chaacte'rized in that thecolloidal solution has added thereto a small amount 01' a soitenlns agent.

10. The method substantially as/descrihed in claim 2, but furthercharacterised in that the colloidal solution has added thereto a small amount of a synthetic resin dispersed in water.

-DONALD H. POWERS.

WILLIAM 'J. HARRISON.

summons crrm The following references are of record in the tile 0! this patent:

. -12 um'rm s'rs'rss ram Number 20 Number Name Date Britton D36. 18. 19 33 Ubbelohde my 17.1937 King et a1. June 0, 1331 Vaughn Oct. 2", 1938 McGrecor Sept. 17, 1940 Bird June 3, 1941 Marshall June 9. 1942 White June 9. 18 42 Dennison Am". 27. 1043 Christensen May 1914 Gilbert er. a1. Oct. 24, 1344 wmw May a, 1645 Kirk A 333, 1945 Vans O .28. 1946 Powers et al. June it. 19;; FOREIGN PATENTS Country Date Great Britain Oct. 23, 1936 

1. THE METHOD OF TREATING TEXTILE FABRICS TO PROVIDE THEM WITH A SLIP-RESISTANT FINISH WHICH COMPRISES APPLYING TO THE OUTER SURFACES OF SAID FABRIC AN AQUEOUS COLLOIDAL SOLUTION OF SILICA CONSISTING OF A STABLE SILICA SOL IN AN AMOUNT SUFFICIENT TO SUPPLY FROM 0.1 TO 5% OF SILICA BASED ON THE WEIGHT OF THE FABRIC AND SUFFICIENT TO FORM A FILM OF SILICA ON THE SURFACE OF SAID FABRIC UPON DRYING, AND THEN DRYING THE TREATED FABRIC BY EXPOSURE TO TEMPERATURES OF AT LEAST 200*F. WITHOUT ALLOWING SAID SOLUTION TO CONVERT TO A GEL, WHEREBY AN INORGANIC RESINOUS FILM COMPOSED OF PARTICLES OF SILICA IS FORMED THEREON. 